在1992年在加利福尼亚州阿纳海姆市举行的SHARE 78会议M028上，自动化远程站点恢复任务小组提出了七个可恢复性层，这就是后来被广泛引用的share78国际标准。

The 7-tiers of Disaster Recovery

The Seven Tiers of Disaster Recovery was first defined in 1992 by SHARE. (SHARE Inc. is an independent user group providing IBM customers with services, education and professional networking.)

The Seven Tiers was defined to help identify the various methods of recovering mission-critical computer systems as required to support business continuity.

Business Continuity Planning (BCP) and Disaster Recovery Specialists today continue to use the 7-Tier concept as it is very useful in illustrating continuity capabilities and at a high level, their associated costs. The definitions for the various Tiers have been updated as technology has evolved in support of today's business requirements and their associated Recovery Time Objectives (RTO) and Recovery Point Objectives (RPO). The seven tiers of business continuity solutions offer a simple method to define your current service levels, risks and where you really want or need to be.

（SHARE于1992年首次定义了灾难恢复的七个层级。（SHARE Inc.是一个独立的用户组，为IBM客户提供服务，教育和专业网络。）

定义了七个层是为了帮助确定支持业务连续性所需的各种恢复关键任务计算机系统的方法。

今天，业务连续性计划（BCP）和灾难恢复专家继续使用7层概念，因为它在说明连续性功能和较高的相关成本方面非常有用。随着技术的发展以支持当今的业务需求及其相关的恢复时间目标（RTO）和恢复点目标（RPO），各种等级的定义也已更新。七层业务连续性解决方案提供了一种简单的方法来定义您当前的服务级别，风险以及您真正想要或需要的位置。）

Tier 0: No off-site data

Businesses with a Tier 0 business continuity solution have no Business Continuity Plan. There is no saved information, no documentation, no backup hardware, and no contingency plan. The time necessary to recover in this instance is unpredictable. In fact, it may not be possible to recover at all.

（具有Tier 0业务连续性解决方案的企业没有业务连续性计划。没有保存的信息，没有文档，没有备份硬件，也没有应急计划。在这种情况下恢复所需的时间是不可预测的。实际上，可能根本无法恢复。）

Tier 1: Data backup with no hot site

Businesses that use Tier 1 continuity solutions back up their data and send these backups to an off-site storage facility. The method of transporting these backups is often referred to as "PTAM" - the "Pick-up Truck Access Method." Depending on how often backups are created and shipped, these organizations must be prepared to accept several days to weeks of data loss, but their backups are secure off-site. However, this tier lacks the systems on which to restore data.

（使用第1层连续性解决方案的企业备份其数据，并将这些备份发送到异地存储设施。传输这些备份的方法通常称为“ PTAM”-“皮卡车访问方法”。 根据创建和交付备份的频率，这些组织必须准备好接受几天到几周的数据丢失，但是他们的备份是安全的异地。但是，此层缺少还原数据的系统。）

Tier 2: Data backup with a hot site

Businesses using Tier 2 business continuity solutions make regular backups on tape. This is combined with an off-site facility and infrastructure (known as a hot site) in which to restore systems from those tapes in the event of a disaster. This solution will still result in the need to recreate several hours or even days worth of data, but the recovery time is more predictable.

（使用第2层业务连续性解决方案的企业在磁带上进行常规备份。这与异地设施和基础结构（称为热站点）结合在一起，在发生灾难时可以从这些磁带中还原系统。该解决方案仍然需要重新创建几个小时甚至几天的数据，但是恢复时间更可预测。）

Tier 3: Electronic vaulting

Tier 3 solutions build on the components of Tier 2. Additionally, some mission critical data is electronically vaulted. This electronically vaulted data is typically more current than that which is shipped via PTAM. As a result there is less data recreation or loss after a disaster occurs.

The facilities for providing Electronic Remote Vaulting consists of high-speed communication circuits, some form of channel extension equipment and either physical or virtual Tape devices and an automated tape library at the remote site. IBM's Peer-to-Peer VTS and Sun's VSM Clustering are two examples of this type implementation.

（第3层解决方案基于第2层的组件。此外，一些关键任务数据已通过电子方式存储。这种电子存储的数据通常比通过PTAM传输的数据具有更高的最新性。结果，灾难发生后的数据重新创建或丢失减少了。

提供电子远程保管库的设施包括高速通信电路，某种形式的通道扩展设备以及物理或虚拟磁带设备以及远程站点上的自动磁带库。IBM的对等VTS和Sun的VSM集群就是这种类型的实现的两个示例。）

Tier 4: Point-in-time copies

Tier 4 solutions are used by businesses that require both greater data currency and faster recovery than users of lower tiers. Rather than relying largely on shipping tape, as is common on the lower tiers, Tier 4 solutions begin to incorporate more disk based solutions. Several hours of data loss is still possible, but it is easier to make such point-in-time (PiT) copies with greater frequency than tape backups even when electronically vaulted.

（与较低层的用户相比，需要更大数据流量和更快恢复的企业使用第4层解决方案。第4层解决方案不再像较低层那样普遍依赖运输磁带，而是开始结合更多基于磁盘的解决方案。仍然可能会损失数小时的数据，但是与磁带备份相比，即使以电子方式存储，也更容易以更高的频率制作此类时间点（PiT）副本。）

Tier 5: Transaction integrity

Tier 5 solutions are used by businesses with a requirement for consistency of data between the production and recovery data centers. There is little to no data loss in such solutions, however, the presence of this functionality is entirely dependent on the application in use.

（企业使用第5层解决方案，要求生产和恢复数据中心之间的数据一致性。在这种解决方案中几乎没有数据丢失，但是，此功能的存在完全取决于所使用的应用程序。）

Tier 6: Zero or near-Zero data loss

Tier 6 business continuity solutions maintain the highest levels of data currency. They are used by businesses with little or no tolerance for data loss and who need to restore data to applications rapidly. These solutions have no dependence on the applications or applications staffs to provide data consistency.

Tier 6 solutions require some form of Disk Mirroring. There are various synchronous and asynchronous solutions available from the mainframe storage vendors. Each solution is somewhat different, offering different capabilities and providing different Recovery Point and Recovery Time objectives.

Often some form of automated tape solution is also required. However, this can vary somewhat depending on the amount and type of data residing on tape.

（第6层业务连续性解决方案保持最高水平的数据流通性。那些对数据丢失几乎没有容忍或需要快速将数据恢复到应用程序的企业使用它们。这些解决方案不依赖于应用程序或应用程序人员来提供数据一致性。

第6层解决方案需要某种形式的磁盘镜像。大型机存储供应商提供了各种同步和异步解决方案。每个解决方案有所不同，提供不同的功能并提供不同的恢复点和恢复时间目标。

通常，还需要某种形式的自动磁带解决方案。但是，这可能会有所不同，具体取决于磁带上数据的数量和类型。）

Tier 7: Highly automated, business integrated solution

Tier 7 solutions include all the major components being used for a Tier 6 solution with the additional integration of automation. This allows a Tier 7 solution to ensure consistency of data above that which is granted by Tier 6 solutions. Additionally, recovery of the applications is automated, allowing for restoration of systems and applications much faster and more reliably than would be possible through manual business continuity procedures.

 （第7层解决方案包括用于第6层解决方案的所有主要组件以及附加的自动化集成。这使Tier 7解决方案可以确保数据的一致性高于Tier 6解决方案所授予的数据。此外，应用程序的恢复是自动进行的，与通过手动业务连续性程序实现的恢复相比，可以更快，更可靠地恢复系统和应用程序。）

Recovery Objectives

The Recovery Time Objective (RTO) and Recovery Point Objective (RPO) along with cost are important criteria when evaluating the right solutions.

• Recovery Time Objective:

  The Recovery Time Objective (RTO) describes the time within which business functions or applications must be restored (includes time before disaster declared and time to perform tasks).

• Recovery Point Objective:

  The Recovery Point Objective (RPO) describes the point in time to which data must be restored to successfully resume processing (often thought of as time between last backup and when outage occurred).

Many solutions are available. Choosing the right ones requires that you balance the cost of the solution against the costs associated with downtime and lost data. Some amount of data loss may be acceptable if the data can be captured from other sources or easily recreated.

This is not a one-size fits all solution. The very best practice for any organization is to implement an appropriate blending of these tiers. In this way, you can implement the correct level of Disaster Recovery protection at the lowest possible cost. A single solution or technology isn't usually the best choice for all applications.

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恢复目标

在评估正确的解决方案时，恢复时间目标（RTO）和恢复点目标（RPO）以及成本是重要的标准。

• 恢复时间目标：

  恢复时间目标（RTO）描述了必须恢复业务功能或应用程序的时间（包括宣布灾难之前的时间和执行任务的时间）。

• 恢复点目标：

  恢复点目标（RPO）描述了数据必须还原到的时间点才能成功恢复处理（通常认为是上次备份到发生中断之间的时间）。

有许多解决方案可用。选择正确的解决方案要求您在解决方案的成本与停机时间和数据丢失相关的成本之间取得平衡。如果可以从其他来源捕获数据或轻松地重新创建数据，则可能会造成一定程度的数据丢失。

这不是一种千篇一律的解决方案。对于任何组织来说，最佳实践都是对这些层进行适当的融合。这样，您可以以最低的成本实施正确级别的灾难恢复保护。单一解决方案或技术通常不是所有应用程序的最佳选择。）